Wellcome Trust Clinical Research Facility, University Hospitals Birmingham NHS Foundation Trust, Birmingham B15 2TH, UK.
Int J Cardiol. 2011 Oct 20;152(2):184-91. doi: 10.1016/j.ijcard.2010.07.013. Epub 2010 Aug 10.
Limb electrodes for the 12 lead ECG are routinely placed on the torso during exercise stress testing or when limbs are clinically inaccessible. It is unclear whether such electrode modification produces ECG changes in healthy male or female subjects that are clinically important according to the 2009 AHA, ACCF, HRS guidelines. We therefore measured whether ECG modification produced clinically important or false positive ECG changes e.g., appearance of Q waves in leads V(1-3), ST changes greater than 0.1 mV, T wave changes greater than 0.5 mV (frontal plane) or 1 mV (transverse plane), QRS axis shifts or alterations to QTc/P-R/QRS intervals.
The 12 lead ECG was measured in 18 healthy and semi-recumbent subjects using the standard and Takuma modified limb placements.
In the frontal plane we demonstrate that the modification of limb electrode placement produces small Q, R and T wave amplitude and QRS axis changes that are statistically but not clinically significant. In the transverse plane it produces no statistically or clinically significant changes in the ECG or in ST segment morphology, P-R, QRS or QTc intervals.
We provide better and more robust evidence that routine modification of limb electrode placement produces only minor changes to the ECG waveform in healthy subjects. These are not clinically significant according to the 2009 guidelines and thus have no effect on the clinical specificity of the 12 lead ECG.
在运动应激试验或肢体临床上无法触及的情况下，常规将肢体导联电极放置在躯干上进行 12 导联心电图检查。目前尚不清楚这种电极修改是否会在健康男性或女性受试者中产生临床上重要的心电图变化，根据 2009 年 AHA、ACCF、HRS 指南。因此，我们测量了心电图修改是否会产生临床上重要或假阳性的心电图变化，例如 V（1-3）导联出现 Q 波、ST 变化大于 0.1 mV、T 波变化大于 0.5 mV（额面）或 1 mV（横面）、QRS 轴偏移或 QTc/P-R/QRS 间期改变。
使用标准和 Takuma 改良的肢体放置方法，在 18 名健康和半卧位受试者中测量 12 导联心电图。
在额面，我们证明肢体电极放置的修改会产生小的 Q、R 和 T 波幅度和 QRS 轴变化，但在统计学上但不是临床上有意义。在横面，它不会对心电图或 ST 段形态、P-R、QRS 或 QTc 间期产生统计学或临床上有意义的变化。
我们提供了更好和更有力的证据，证明常规修改肢体电极放置只会在健康受试者的心电图波形中产生较小的变化。根据 2009 年的指南，这些变化在临床上并不重要，因此不会对 12 导联心电图的临床特异性产生影响。
